1. Field Of The Invention
The present invention relates to a method and composition for temporarily plugging a wellbore or subterranean formation
2. Prior Art
The performance of remedial treatments on producing oil and gas wells require a method of effecting well control or zonal isolation. Methods of well control include such means as weighted fluids, mechanical devices such as packers, bridge plugs or mechanical diverters, cement plugs and aqueous polymer gel plugs.
The aqueous polymer gel plugs offer an alternative to the mechanical devices and may be more economical or practical than a mechanical device in many instances. The polymer gel plugs use water soluble polymers dispersed as a colloidal, aqueous solution to temporarily plug or seal a permeable zone or formation adjacent to a wellbore or form a plug in the wellbore. The water soluble polymers typically are high molecular weight natural polysaccharides such as guar gum, derivatized guars and derivatized cellulose. When the polysaccharides hydrate, they form viscous gels.
In certain instances it may be necessary to create a temporary plug in a formation which is subject to significant damage when contacted by an aqueous fluid or which might be damaged by the residue remaining after treatment with an aqueous gel. In such a situation it would be desirable to effect plugging with a non-aqueous fluid such as a hydrocarbon that could be caused to viscosify. It would also be desirable to minimize any residue present after the treatment that could damage formation permeability.